This invention is concerned with the improvement of a pneumatically driven nut running tool, such as an impact wrench, with directional torque selector mechanism which enables the operator to effect a change in the torque output value of the tool as needed according to the work involved and the intended torquing direction.
A tool of this improved nature is especially desirable for wheel work in auto service stations in applying or removing fasteners such as lug bolts, as well as in other applications.
The full torgue capacity of the tool is often required in a reverse direction to remove overtightened or frozen lug bolts; whereas a lesser torque is desired to be applied at times in a forward direction to avoid overtightness and possible damage to components of the vehicle such as the rotor in disc brake applications when installing the bolts.
A general object of the invention is to provide a pneumatically driven nut running tool, such as an impact wrench, with directional torque and torque value control means which will enable the operator to select not only the direction of torque output but also to regulate the value of the output.
A further object is to provide in a rotary impact wrench a directional flow control valve of the back-and-forth push type for controlling the direction of air flow to the motor of the tool and having integral regulatory means for controlling the volume of air flow to the motor.
In accordance with the invention there is provided a pneumatically powered nut running tool comprising a reversible rotary air motor, a throttle valve for admitting supply air to the tool, a manually slidably positionable control valve located between the throttle valve and the motor for controlling directional application and volume of supply air flow to the motor, the control valve being slidable to a first position in which it directs supply air at full volume flow from the throttle valve to a forward driving side of the motor and being slidable to an opposite second position in which it directs supply air at full volume flow from the throttle valve to a reverse driving side of the motor, manipulative means carried by the control valve selectively operable for adjustably shortening the length of the control valve, and the control valve in its adjusted condition being slidable to a third position in which it directs supply air at a reduced volume flow from the throttle valve to the forward driving side of the motor, means for preventing sliding of the control valve beyond its first and second positions, and other means for preventing sliding of the control valve in its adjusted condition beyond its third position.